1. Field of the Invention
The present invention relates to a magnetic head including a slider and installed in a hard disk drive, a magnetic recording/reproducing apparatus equipped with the magnetic head, and a method of manufacturing the same. More specifically, in the magnetic head, the torque required for starting a recording medium is reduced, and a magnetic recording/reproducing thin-film element disposed in the end portion on the trailing side of said slider is protected to reduce the size of an element recess.
2. Description of the Related Art
FIG. 8 is a perspective view showing a conventional magnetic head used in a hard disk drive or the like when the head is placed such that the surface opposing the recording medium faces upward, namely, the upper surface of the magnetic head H shown in FIG. 8 faces the recording surface of a hard disk being a magnetic recording medium.
In the magnetic head H, the upstream side (i) relative to the disk-moving direction X is called a leading side while the downstream side (ii) relative to the same is called a trailing side. The magnetic head H includes a slider 1 formed of a ceramic material or the like, and the slider 1 is equipped with a thin-film element 3 on the end surface 2 on the trailing side (ii). The thin-film element 3 has a MR head (reading head) which reads magnetic signals by detecting leakage magnetic fields from a recording medium such as a hard disk while utilizing the magnetoresistance effect, and has an inductive head (recording head) in which a coil and other elements are patterned.
In the slider 1, the portion to oppose the disk includes an air groove 7 and rail portions 4 forming both side walls of the groove, and the top surfaces of the rail portions 4 are opposing surfaces (Air Bearing Surface; ABS) 5. Each of the opposing surfaces 5 has a crown with a predetermined curvature, and a slope 6 in the end portion on the leading side.
The slider 1 of the magnetic head H is supported by a flexure which is fixed to the tip of a load beam, and is urged to the disk by an elastic force of the load beam derived from a plate spring. Such a magnetic head H is used in a hard disk drive of a so-called CSS (Contact Start/Stop) type, and the opposing surfaces 5 of the slider come into contact with the recording surface of the disk by the elastic force when the disk is at a standstill. When the disk is started, an air stream is introduced along the disk-moving direction (X direction) into the space between the slider 1 and the surface of the disk, the opposing surfaces 5 then receive a floating force derived from the air stream, and the slider 1 floats at a height slightly distant from the disk surface.
In the floating situation, the head slants such that the portion on the leading side (i) is situated higher from the disk surface than the portion on the trailing side (ii). In this floating attitude, magnetic signals from the disk are detected by the MR head of the thin-film element 3, or magnetic signals are recorded by the inductive head.
A disk-driving motor installed in a CSS-type hard disk drive requires a starting torque great enough for securely causing the disk and slider to slide. When the starting torque required for starting the disk and slider is greater, the motor used in the hard disk drive must be larger. Accordingly, reduction in size of the equipment will be limited, and the power consumption will be large.
The starting torque required for starting the disk depends on the static frictional force between the opposing surfaces 5 of the slider 1 and the surface of the disk. Accordingly, reducing the starting torque requires reducing the static frictional force.
In hard disks as conventional recording media, the surface is relatively irregular, and in general, the center line mean roughness R.sub.ad of the disk plane is approximately 10 nm. Due to this, even if the opposing surfaces 5 of the slider 1 are relatively smooth, the real contact area between the disk surface and the opposing surfaces 5 of the slider 1 can be decreased, and as a result, the static frictional force can be reduced.
In recent hard disks for high recording densities, however, the disk surface have been made increasingly smoother, and the center line mean roughness R.sub.ad (according to JIS; Japanese Industrial Standard) of the disk plane has tended to be reduced. When the center line mean roughness R.sub.ad of the disk plane is large, protrusions irregularly appear on the disk surface. Accordingly, the slider may contact such protrusions causing damage of the disk surface when the magnetic head takes the floating attitude for magnetic recording/reproducing. In particular, since the hard disk for high-density recording should have more reduced spacing between the thin-film element 3 and the disk plane, generation of such irregular protrusions must be prevented. For the above-described reasons, a high-density recording hard disk is manufactured so that it has a smooth disk surface that is almost the same as a mirror surface.
In a disk drive for a hard disk which has a smoother disk surface and which is capable of coping with high-density recording, therefore, the opposing surfaces 5 of the slider 1 should be made rougher to decrease the real contact area between the disk plane and the opposing surfaces 5.
In such a magnetic head H of the type shown in FIG. 8, however, achieving an appropriate roughness of the opposing surfaces 5 alone is extremely difficult.
For example, an attempt to make the opposing surfaces 5 of the slider 1 rough by dry etching may result in damage to the thin-film element 3 due to the influence of the dry etching. This problem occurs since the thin-film element 3 is generally formed of a material having a relatively high etching rate, such as aluminum oxide or permalloy.
FIG. 9 is a side view showing only the portion on the trailing side (ii) of the magnetic head shown in FIG. 8. When the opposing surfaces 5 are dry-etched, the exposed portion 8 as the upper surface of the thin-film element 3 is also etched so that the level of the upper surface is lowered by a height of h2, and a portion 3' of the thin-film element surrounded by the dotted line is removed. When such an element recess with a height of h2 is generated, the spacing loss between the thin-film element 3 and the disk plane increases, leading to a reduction in signal-recording efficiency and reading sensitivity. In other cases, the thin-film element 3 may be destroyed, and normal reading and recording may become impossible.
Alternatively, a mechanical polishing treatment can be employed to make the opposing surfaces 5 rough. Such a mechanical polishing treatment, however, cannot adjust the center line mean roughness R.sub.ah to an appropriate degree, the maximum roughness R.sub.max (according to JIS) becomes large, irregular protrusions are generated on the opposing surfaces 5, and the disk surface may thereby readily be damaged. Further, such a mechanical polishing treatment has a further higher possibility of damaging the thin-film element 3.